(CNS) Central Nervous System

• (CNS) Central nervous system: In vertebrates (animals with backbones) this consists of the brain and the spinal chord only. In mammals, the CNS is connected to the body by sensory neurones and motor neurones
• The (CNS) Central Nervous System coordinates the response
• The CNS is a coordination centre - it receives information from the receptors and then coordinates a response. The response is carried out by effectors
• CNS e.g 1. A small bird is eating some seed when, out of the corner of its eye, it spots a cat skulking towards it (the stimulus)
• CNS e.g 2. The receptors in the bird's eye are stimulated. Sensory neurones carry the information from the receptors to the CNS
• CNS e.g 3. The CNS decides what to do about it
• CNS e.g 4. The CNS sends information to the muscles in the bird's wings (the effectors) along the motor neurones.
• CNS e.g 5. The wing muscles contract and the bird flies away to safety
• Stimulus -> Receptor -> CNS -> Motor neurone -> Effector -> Response